1. Field of the Invention
The present invention generally relates to the use of optical techniques such as Photogrammetry and laser tracking to make precise measurements of part or workpiece features, and deals more particularly with a traveling reference system that provides precise Photogrammetry camera placement information.
2. Description of the Related Art
A variety of processes have been employed to measure one or more surfaces or features of a part or workpiece. Touch probes have commonly been used to make contact measurements of part features or workpiece surfaces. Computer controlled coordinate measuring machines use touch probes to contact surfaces on a part and electronically record the measurements. More recently, “touchless” technologies, such as laser tracking, have been used to measure surfaces. Laser trackers use a laser distance meter, encoders and software to calculate, store and display the 3-dimensional position of a mirrored target which is positioned on or near the surface being measured. A beam steering system senses movement of the mirrored target and directs servomotors to track the target. The tracker follows the target over features, updating the position many times per second. Laser trackers are relatively slow, particularly when measuring large or complex parts, such as a fuselage section of an aircraft.
Photogrammetry has also been used to measure surfaces using photo-grammes comprising electronically stored images recorded by digital cameras or radiation sensor based scanners.
Each of the measuring techniques described above is less than satisfactory in various respects, particularly in terms of length of time required to measure large or complicated parts.
Accordingly, there is a need for a surface measuring system that alleviates one or more of these problems, and allows relatively rapid, accurate measurements of part surfaces and features. The present invention is directed toward satisfying this need.